Description Benjamin Pasero 2008-06-02 09:51:12 EDT

Eclipse 3.4 RC1

I tried using the ViewerDropAdapter for my TreeViewer together with the new URLTransfer in SWT since 3.4. I was not able to get a valid DND feedback for some reason. See the following snippet as example:

/*******************************************************************************
 * Copyright (c) 2006 Tom Schindl and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Tom Schindl - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.snippets.viewers;

import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerDropAdapter;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.dnd.URLTransfer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

import java.util.ArrayList;

/**
 * A simple TreeViewer to demonstrate usage
 *
 * @author Tom Schindl <tom.schindl@bestsolution.at>
 */
public class Snippet002TreeViewer {
  private class MyContentProvider implements ITreeContentProvider {

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(java.lang.Object)
     */
    public Object[] getElements(Object inputElement) {
      return ((MyModel) inputElement).child.toArray();
    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.IContentProvider#dispose()
     */
    public void dispose() {

    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.IContentProvider#inputChanged(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
     */
    public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {

    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(java.lang.Object)
     */
    public Object[] getChildren(Object parentElement) {
      return getElements(parentElement);
    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.ITreeContentProvider#getParent(java.lang.Object)
     */
    public Object getParent(Object element) {
      if (element == null) {
        return null;
      }

      return ((MyModel) element).parent;
    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.ITreeContentProvider#hasChildren(java.lang.Object)
     */
    public boolean hasChildren(Object element) {
      return ((MyModel) element).child.size() > 0;
    }

  }

  public class MyModel {
    public MyModel parent;
    public ArrayList child = new ArrayList();
    public int counter;

    public MyModel(int counter, MyModel parent) {
      this.parent = parent;
      this.counter = counter;
    }

    public String toString() {
      String rv = "Item ";
      if (parent != null) {
        rv = parent.toString() + ".";
      }

      rv += counter;

      return rv;
    }
  }

  public Snippet002TreeViewer(Shell shell) {
    final TreeViewer v = new TreeViewer(shell);
    v.setLabelProvider(new LabelProvider());
    v.setContentProvider(new MyContentProvider());
    v.setInput(createModel());

    int operations = DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK;
    v.addDropSupport(operations, new Transfer[] { URLTransfer.getInstance() }, new ViewerDropAdapter(v) {
      public boolean performDrop(Object data) {
        return true;
      }

      public boolean validateDrop(Object target, int operation, TransferData transferType) {
        return true;
      }

      public void dragEnter(DropTargetEvent e) {
        super.dragEnter(e);

//        if (e.detail == DND.DROP_NONE)
//          e.detail = DND.DROP_LINK;
      }
    });
  }

  private MyModel createModel() {

    MyModel root = new MyModel(0, null);
    root.counter = 0;

    MyModel tmp;
    for (int i = 1; i < 10; i++) {
      tmp = new MyModel(i, root);
      root.child.add(tmp);
      for (int j = 1; j < i; j++) {
        tmp.child.add(new MyModel(j, tmp));
      }
    }

    return root;
  }

  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    new Snippet002TreeViewer(shell);
    shell.open();

    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }

    display.dispose();
  }
}


It only works when I override dragEnter() to set the detail accordingly.